Gianfranco Zola has been re-admitted to hospital after undergoing surgery to a cure a gallstone problem.
The Chelsea assistant manager had an operation last week that caused him to miss Monday's loss against Manchester United in the FA Cup fifth round.
But Zola has suffered complications from the operation and has been hospitalised again as a result.
Zola will therefore miss Thursday night's Europa League clash against Malmo at Stamford Bridge.
It remains to be seen whether the Italian will play any part in Chelsea's preparations for Sunday's Carabao Cup Final against Manchester City or be available to take his place on the bench at Wembley.
Chelsea will allow Zola as much time as he needs to make a full recovery and do not want to put a timescale on his return.
The news could complicate Chelsea's pending decision over the bleak future of under-fire manager Maurizio Sarri.
The Blues boss is on the brink of the sack with the board, players and fans all rapidly losing faith in the Italian.
Zola would be a candidate to replace Sarri at the helm on an interim basis until the end of the season.
But his recent health issues could emerge as a factor should, as is looking increasingly likely, Chelsea fire Sarri when the club consider potential names of who can steady the ship.